(1) Field of the Invention
The present invention relates to a magnetic disk device, and more particularly to a magnetic disk drive apparatus in which a Contact Start Stop Mode (hereinafter abbreviated as "CSS mode") and a Head Load/Unload Mode (hereinafter abbreviated as "HLU mode") are combined for ensuring a longer life and enhancing reliability of the device. In the CSS mode, a data storage medium (hereinafter simply referred to as "medium") starts or stops its rotation with a magnetic head being in contact with the medium and, in the HLU mode, the medium starts or stops its rotation with the magnetic head being separated from the medium.
(2) Description of the Related Art
The increased demand in recent years for higher capacity necessitates the reduction in the flying-height of the magnetic head from the medium and this, coupled with an improvement in a profile irregularity of the medium, presents a potential problem of unintentional contact or adhesion between the magnetic head and the medium. In utilizing the magnetic disk drive apparatus in a recent laptop type computer, it is required that power consumption be kept low since such a computer is typically battery-powered and that, in order to meet such requirement, a semi-stop mode be employed whereby the parts, excepting the minimum necessary functional elements but including those associated with the medium, are stopped during the non-access period. Also, the magnetic disk drive apparatus for such a computer is required to have high shock-proof characteristics because of its portable nature.
In view of the above, there have existed two kinds of conventional magnetic disk drive apparatus in terms of the modes they utilized. The first kind is one in which both the structure at the side of the drive mechanism including the magnetic head itself and the structure at the side of the medium are improved whereby the CSS mode is used to achieve the reliable performance. The other kind is one which is a more positive method and in which, during both the stopped state and the semi-stopped state of the magnetic disk drive apparatus, a loading/unloading mechanism is utilized and the magnetic head is allowed to be separated from the medium in HLU mode resulting in the achievement of the reliable performance.
In the first kind in which the characteristics at the side of the magnetic head and at the side of the medium are improved and the CSS mode is used, there is a limit in the use of the semi-stop mode because of the large number of slidings which occur when the semi-stop mode is used to stop the rotation of the medium during the non-access period in order to reduce power consumption.
In the second kind in which the HLU mode is used for separating the magnetic head from the medium, although this is ideal when the semi-stop mode is used, there is a problem in that it will be very difficult to reliably perform the HLU mode operation in case the interruption of power suddenly occurs.